Firing mechanism for a rifle



Sept. 6, 1955 A. F. GAlDos 2,716,923

FIRING MECHANISM FOR A RIFLE MJZMM a. mam

Sept. 6, 1955 A. F. GAlDos 2,716,923

FIRING MECHANISM FOR A RIFLE Original Filed Feb. l, 1950 v 3 Sheets-Sheet 2 I ,f :l-1 E'. 4 62 loo f 112 m2 W/ ln m l f1 E'. .5-

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Sept. 6, 1955 A. F. GArDos 2,716,923

FIRING MECHANISM FOR A RIFLE Original Filed Feb. l, 1950 3 Sheets-Sheet 3 A113112 mLEUiE-lm United States Patent y"Oli 2,716,923 Patented Sept. 6, 1955 ice FG MECHANISM FOR A RIFLE Alonzo F. Gaidos, Redwood City, Calif.

Original application February 1, 1950, Serial No. 141,801. Divided and this application December 8, 1952, Serial No. 324,857

4 Claims. (Cl. 89-140) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

The present invention relates to an improvement in a firing mechanism for an automatic rie and more par- -ticularly to the type of rifle as shown in my copending application, Serial No. 141,801, tiled February l, 1950, of which this application is a division.

The object of this invention is to improve and simplify the construction and operation offlring mechanisms in a iirearm and also to provide a fire control trigger which permits smooth and easy action.

One of the objects of this invention is to provide a rie with means whereby automaticlor semi-automatic firing is accomplished by the same trigger independently of selector devices.

Another object of this invention is to provide an automatic and semi-automatic firearm with a primary sear `and a secondary sear that are operable independently of `each other with a minimum of parts and that cooperate with a striker or other means of firing a firearm.

Still another object of this invention is toprovide a rie adapted for automatic or semi-automatic tiring with a safety to lock the semi-automatic sear which is easily A operated.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying -drawings in which:

Fig. l is a longitudinal cross-sectional view of the receiver with the bolt in the locked battery position and `the striker in the cocked position;

Fig. 7 is a right side enlarged view of the semi-automatic Sear;

Fig. 8 is a perspective view of the trigger assembly and latch;

Fig. 9 is an enlarged cross-sectionalview taken on line 9 9 of Fig. ll;

Fig. 10 is a perspective view of the automatic lever;

Fig. 1l is a cross-sectional View taken on line 11 11 Y of Fig. l; and

Fig. 12 is a perspective view of the actuator bar. The particular embodiment of the invention chosen for -the purpose of illustration as shown in the drawings cornlprises a receiver 12, a bolt assembly 13, a'trigger mechanism 14 and a receiver housingt15.

Receiver 12 is provided with a threaded longitudinal recess 16 in the upper rear end thereof to threadably receive a striker retainer 17. The forward end of re- =rear sight 21.

A longitudinal bore 22 is provided in the upper forward part of receiver 12 extending out through boss 18 to receive bolt assembly 13. Receiver All2 has a downwardly depending rectangular portion 23 being provided with a vertical magazine opening 24 andan angular slot 25 to receive a lock 26 which will be described later.

Extending forwardly from threaded recess 16 a longitudinal bore 27 is provided to receive a striker 28. Forwardly of longitudinal bore 27 a small bore 29 is provide-d to slidably support a reduced end 30 on striker 28. Forwardly of bore 29 and connected to bore 22 an enlarged bore 31 is provided to'receive a buffer 32. On the forward upper right side of receiver 12 angularly disposed above the axis, there is a longitudinal slot 33 to permit ejection of a red round and for the accommodation of a bolt handle 34. On the rear surface of receiver portion 23 a transverse slot 35is provided t0 receive a retainer 36 of a bolt return spring rod 37.

Depending from the lower end of receiver 12, a rectangular projection 38 is provided with a vertical, cylindrical recess 40 to receive a trigger retaining clamp 39. Centrally and vertically disposed in recess 4i?, a threaded hole 41 is provided to receive a trigger guard screw 42. Forwardly of projection 38 a depending lug 43 on receiver 12 is provided with a transverse slot 44 to receive a retainer 45 of rod 37. A helical bolt return spring 46 `surrounds bolt returnspring rod 37 for a purpose to be later described. A pair of longitudinally disposed holes 47 is provided in projection 38 to receive sear return plungers 48. A transverse hole 49 is provided approximately at the rear of receiver 12 below bore 27 and at right angles therewithV to receive a safety lever 50i. Forwardly of hole 49 and in line therewith a transverse hole 51 is provided to receive a sear pin 52. Sear pin 52 is provided for mounting an automatic sear 53 and a semiautomatic sear 54, such sears being pivotally mounted therein. Forwardly of hole 51 another transverse hole 55 is provided to receive a stop pin 56 which limits the counterclockwise movement of Sear 54.

Striker 28 comprises an enlarged diametrical rear end S7 having an angular projection or lug 58 on the bottom end thereof forming a hook for the engagement of theV sears. A cylindrical recess 59 is provided in the rear end of striker 28 to receive the forward end of a striker spring 60. 'Striker retainer 17 is provided with a cylindrical bore 61.0ppositely disposed to recess 59 to receive the rear end of striker spring 60. Striker retainer 17 is provided with a knurled head 62 to permit such retainer to be assembled in threaded recess 16.

Aibolt 63 of bolt assembly 13, cylindrical in contour, is provided with a firing pin tunnel 64 therein toreceive a firing pin 65 of a conventional shape and such bolt is `reciprocable in bore 22. A tiring pin spring 66 surrounds pin 65 thereby biasing such pin rearwardly. Bolt 63 is providedonthe rear end thereof with vertically positioned ways 67 to receive aring pin retainer 68. Firing pin 65 has a reduced diametrical portion 69 on the rear end thereof which is slidably received in` a hole 70 of retainer 68.

VBolt 63 is provided with a longitudinal dove-tailed slot 71 on the forward right side angularly disposed above the horizontal axis thereof to receive bolt handle 34. A longitudinal slot 72 with a semi-cylindrical bottom is provided oppositely opposed to slot 71 on the left side of bolt 63 in the forwardl end thereof to slidably receive .an ejector 73. Bolt 63 is provided with a longitudinal shallow lslot 74 rearwardly of and aligned with slot .71

therein to receive a bolt handle strap 75. Strap is provided with a protruding detent 76 which nests in a recess 77 in bolt 63 thereby retaining bolt handle 34 in position. Rearwardly of and aligned with slot 72, there is provided an ejector stop clearance longitudinal slot 78 to permit free movement of bolt 63 in bore 22 of receiver 12. In the forward part of slot 72 there is provided a raised lug 79 to limit the rearward movement of ejector 73. Ejector 73 has an elongated longitudinal notch 80 arranged for slidable engagement over lug 79 in slot 72. Ejector 73 is urged rearwardly by an ejector spring 81 which is assembled in slot '72 between a rear surface 82 of lug 79 and a rear surface 83 of notch 80. When the bolt assembly 13 moves rearwardly in recoil after discharging a cartridge 84, ejector 73 comes in contact with an ejector stop 85 secured to receiver 12 and protruding into bore 22 whereby ejector 73 stops in relation to the bolt thereby ejecting a spent cartridge 84 out of the receiver 12 through slot 33. Bolt 63 is provided with a transverse slot 86 on the bottom near the rear end thereof to receive lock 26.

Bolt handle 34 has a depending arcuate handle portion 87 which manually operates bolt 63. A longitudinally rectangular slot 88 is provided on bolt handle 34 to receive a spring-biased extractor 89 which is pivotally secured thereto by an extractor pin 90. Retainer 68 is provided with a rectangular open slot 91 on the bottom end thereof to permit a bolt return slide 92 to contact bolt 63. Bolt return slide 92 is provided with a depending body portion 93 having an axial longitudinal hole 94 therein. Bolt return slide 92 is slidably mounted on bolt return rod 37 by means of hole 94. Bolt return slide 92 is biased forwardly by bolt return spring 46 thereby urging bolt 63 into the battery position. Lock 26 is provided with a rectangular open slot 95 angularly disposed on the left side thereof for a purpose to be later described.

Trigger mechanism 14 comprises a trigger guard 96, a trigger 97, a trigger retainer 98, a trigger latch 99, a trigger latch body and an automatic lever 101. Trigger guard 96 is provided with a vertical counterbored hole 102 near the rear end thereof to receive screw 42 thereby securing trigger guard 96 to receiver 12. A longitudinal recess 103 terminating in semi-cylindrical ends 104 is provided on the top of trigger guard 96 to receive trigger retainer 98. A vertically threaded hole 105 is provided in the forward part of recess 103 of trigger guard 96 to receive a trigger retaining screw 106.

Trigger retainer 98 is held in position at the rear end by retainer clamp 39. An elongated longitudinal slot i 107 opening from the rear end is provided in trigger retainer 98 to permit trigger 97 to slidably pass therethrough. Trigger 97 is provided with a conventional type finger piece 108 depending therefrom. A cylindrical longitudinal recess 109 is provided in the rear end of trigger 97 to receive a spring-biased trigger return plunger 110 to urge said trigger forwardly. Opposed longitudinal rectangular slots 111 are provided in trigger 97 to slidably mount such trigger on retainer 98. A rectangular longitudinal seat 112 opening on the top and right side of trigger 97 is provided to receive trigger latch body 100 which is welded thereto or can be made integral therewith. A transverse cylindrical recess 113 is provided on the right side of trigger 97 to receive an automatic lever pin 114 for the pivotal mounting of automatic lever 101.

Trigger latch body 100 is provided with a transverse hole 115 in the center thereof to receive a pin 151 for mounting trigger latch 99 thereon. A transversely raised projection 116 is provided on the rear end of body 100 with a forwardly open slot 117 to receive a flat trigger latch spring 118 which biases trigger latch 99 clockwise. Automatic lever 101 has a transverse hole 119 for mounting such lever on pin 114. Automatic lever 101 is provided with an upstanding arm 120 for the functioning of the semi-automatic sear 54 and a downward projecting arm 121 for imparting pivotal movement to lever 101 in the automatic position of trigger 97.

Automatic sear 53 is provided with a transverse hole 122 for pivotally mounting said sear on scar pin 52. An upstanding projection or hook 123 is provided on the forward top portion of automatic sear 53 for the engagement of projection 58 on striker 28. On the lower left hand side of automatic sear 53 a transverse projecting lug 124 is provided for engagement with latch 99. Semi-automatic sear 54 is provided with a transverse hole 15?. for pivotally mounting such sear on sear pin 52. An upstanding projection or hook 153 is provided on the forward top portion of semi-automatic Sear 54, similar to hook 123 on automatic sear 53, also for the engagement of projection 53 on striker 28. emi-automatic sear 54 is provided with a ledge 125 on the front end thereof for engagement with pin 56 and a lower transverse projecting lug 126 being on the right side similar to lug 124 of sear 53 but oppositely disposed. Semi-automatic sear 54 is also provided with a projection 127 on the rear end arcuately formed for engagement with safety lever 50.

A conventional magazine 128 constructed to receive a double row of cartridges 84 is used with this invention and is removably retained in magazine opening 24 of depending portion 23 by a resilient latch 129 which is pivotally secured to the lower front surface of receiver 12. Latch 129 has a rearwardly projecting horizontal ledge 130 which engages a slot 131 in maga- Zine 123 to position such magazine in the operable p0- sition.

The invention as illustrated in the drawings employs a barrel 132 that is provided with annular ribs 133 equal distance apart to effect cooling of the barrel. The rear end of barrel 132 is of reduced diameter as shown at 134 to be slidably received in bore 22 of receiver 12. Forwardly of end 134 an enlarged diametrical portion 136 is provided to be rotatably received in a recess 137 of a barrel nut 138. The rear end of barrel nut 138 is provided with a threaded recess 139 for securing barrel 132 to the receiver 12 through the medium of threads 19 on receiver 12. The rear portion of the enlarged diameter 136 is provided with a longitudinal keyway 140 on the top and bottom thereof t0 receive a pair of keys 141 which are also receivable in slots 142 of boss 18 of receiver 12 to properly align and position barrel 132 in receiver 12 and also to prevent rotation of such barrel thereby preventing the upsetting of the head space.

Receiver 12 is provided with ways 143 on the left side thereof juxtaposed to slot 25 to slidably receive an actuating bar 144 for reciprocating movement therein. Actuating bar 144 is provided with oppositely disposed ribs 145 that are receivable in ways 143 of receiver 12. A lock actuating stud 146 is provided in the center of bar 144 and protrudes to the right of actuating bar 144 for a purpose to be described later. Oppositely disposed from stud 146, actuating bar 144 is provided with a lever 147 for manually operating lock 26 for a purpose to be described. An elongated slot 148 is provided on the left side of receiver 12 to permit movement of lever 147 therealong. An offset projection 149 protruding to the right on the rear end is provided on actuating bar 144 for a purpose to be later described.

Operations After the insertion of magazine 128, loaded with a double row of cartridges 84, into the magazine opening 24 of receiver 12 and secured therein by latch 129, lock 26 is angularly cammed downwardly out of slot 86 of bolt 63 by pressing forwardly on lever 147 with the thumb of the left hand, such lever being on the left side of the rifle. The bolt 63 is then retracted to the rear by handle 34 permitting the uppermost cartridge 84 in the magazine 128 to enter the chambering spaces between the bolt'63 and the end of thebarrel 132 whereby, on the return of such bolt into-the battery position, the round isA chambered inthe Abarrel and the gun is charged for firing. Before ffiring, the safety lever 50 must be set in the lire position.

Semi-automatic and automatic fire are both accontplished bypullingthetrigger 97 .rearwardly in a horizontal plane varying distances; that is, pulling the trigger only part way'operates the gun in semi-automatic fire, and pulling it all the wayuntil `it stops-operates the gun in automatic fire. When thet trigger 97 is pulled rearwardly, the spring-biased latch 99 pivotally attached thereto, trips the automatic and semi-automatic sears 53 and 54, respectively, thereby releasing the striker 28 allowing the same to come forwardly under the urging of spring 60 strikinglfiring pin v65 in bolt 63 thereby discharging cartridge 84. As the bullet 150 is traveling through the bore of the barrel, the bolt 63 is held securely in the battery position by the lock 26. When the bullet 150 has cleared the bore of the barrel at the muzzle end and while passing through a gas chamber in an actuator cup (not shown), the gaseS escaping from such bore impinge on the inner front wall of such actuator cup thereby forcing said cup forwardly. Actuator cup is coupled with actuator bar 144 thereby moving such bar forwardly, camming the lock 26 downwardly and permitting the bolt to recoil. While the bolt 63 is being driven rearwardly during recoil, the spring-pressed striker 28 is then returned rearwardly and is engaged by the automatic and semi-automatic sears thereby cocking same. At the end of the recoil stroke, the bolt 63 is returned to the battery position under the bias of spring 46 also picking up the uppermost cartridge 84 from the magazine 128 and chambering same in the barrel. The actuator bar is returned rearwardly under the bias of a spring (not shown) thereby camming lock 26 upwardly and locking the bolt 63 in the battery position,

In automatic fire, when the trigger 97 is pulled to the stop position the upstanding arm 120 of automatic lever 101 holds the semi-automatic sear S4 only rearwardly preventing its engagement with striker projection 5S. When the semi-automatic sear is thus held out of engagement, the automatic sear 53 functions normally and is released from the striker 28 by the projection 149 of actuator bar M4 after the actuator cup returns to the normal position under the bias of a spring (not shown) thereby continuing the firing until the trigger is released. In semi-automatic fire when trigger 97 is pulled rearwardly and the latch 99 disconnects both the sears, such latch then overrides the bottom portions 124 and 126 of automatic and semi-automatic sears, respectively, thereby allowing the sears to engage the striker 28 under the bias of plungers 48, and the trigger 97 then has to be returned to its forward position before latch 99 can once again engage the sears to release striker 28.

It will, therefore, be apparent to one skilled in the art that application of the principles of the invention disclosed herein provides novel and improved firearm construction which is outstandingly characterized by a small number of parts with simplicity of configuration in such parts and also in cheapness of manufacture.

I claim:

l. In an automatic firearm, a receiver, a trigger guard, a trigger slidably mounted in said trigger guard having a first and second firing position, a spring-biased semiautomatic sear pivotally mounted on a transverse pin in said receiver, a spring-biased automatic sear pivotally mounted in juxtaposition with said semi-automatic sear on said pin, a spring-biased striker slidably mounted in said receiver, said striker having a downwardly depending lug engageable by both of said sears, pivotal means on said trigger for releasing both of said sears from said striker in said first firing position to obtain semi-automatic firing, an actuator bar slidably mounted in said receiver matic sear is Vdisengaged from the striker engaging position as said bar moves rearwardly, and means on said Ytriggerfor holding said semi-automatic sear'out of engagement from said striker in said second firing position whereby the cyclic release of said striker by said actuating'bar effects automatic firing.

2. vIn an automatic firearm, a receiver, a trigger guard releasablymounted on the underside ofsaid receiver, a trigger slidably mounted in said trigger guard and having a Vfirst and second firing position, a spring-biased semiautomatic searl pivotally mounted on a transverse pin in said receiver, a spring-biased automatic sear pivotally mounted in juxtaposition with said semi-automatic sear on saidfpin, a'spring-biased latch pivotally mounted on said trigger releasably contacting both of said sears, an automatic lever, pivotally mounted on said trigger releasably contacting said semi-automatic sear, a spring-biased striker slidably mounted in said receiver for reciprocal movement between a fired and a retracted position, said striker having a downwardly depending lug engageable by both of said sears, and an actuator bar slidably mounted in said receiver for reciprocating movement therein whereby said automatic sear is disengaged from said striker as said bar moves rearwardly, said latch being arranged to release said sears from said striker in said first firing position and override said sears in said second firing position whereby said lever holds said semi-automatic sear only out of engagement with said striker and said automatic sear reengages said striker thereby permitting said automatic sear to be disengaged from said striker by said bar obtaining automatic firing.

3. In an automatic firearm, a receiver, a trigger guard releasably mounted on the underside of said receiver, a trigger slidably mounted in said trigger guard and having a first and second firing position, a spring-biased semiautomatic sear pivotally mounted on a transverse pin in said receiver, a spring-biased automatic sear pivotally mounted in juxtaposition with said semi-automatic sear on said pin, each of said sears being provided with an upstanding hook in the upper part thereof and a transverse lug on the bottom thereof, a spring-biased latch pivotally mounted on said trigger releasably contacting both of said lugs on said sears, an automatic lever pivotally mounted on said trigger releasably contacting said lug on said semi-automatic sear, a spring-biased striker slidably mounted in said receiver, said striker having a downwardly depending lug engageable by both of said hooks of said sears, and an actuator bar slidably mounted in said receiver for reciprocating movement therein whereby said automatic seary is disengaged from said striker as said bar contacts said lug of said automatic sear as said bar moves rearwardly, said latch being arranged to release said sears from said striker in said first firing position and override said sears in said second firing position whereby said lever holds said semi-automatic sear out of engagement with said striker and said automatic sear reengages said striker only thereby permitting said automatic sear to be disengaged from said striker by said bar obtaining automatic fire.

4. In a firearm having a receiver, a trigger guard depending therefrom, and a striker longitudinally mounted in the receiver for slidable movement between a fired and a cocked position, the combination of a first and second sear juxtaposed on the same transverse axis for independent pivotal movement into and out of cocking engagement with the striker, each of said sears having an outwardly projecting transverse lug, a spring-biased plunger normally urging each of said sears into position to engage the striker during the return movement thereof toward firing position, a trigger slidably mounted in the receiver below said sears for longitudinal movement between an unretracted position and each of two successive firing positions, a sear release member mounted in tbe top of said trigger for limited pivotal movement,

spring means biasing said release member upwardly and rearwardly to normally project in front of said sears for simultaneously camming said seas out of cocking engagement with the striker in response to initial retraction of said trigger, said sear release member being arranged to bypass said sears during retraction of said trigger to said rst iiring position and permit said plungers to return both of said sears into position to simultaneously reengage the .striker and thereby provide semiautomatic fire, a lever pivoted to the side of said trigger and engageable at the upper end thereof with said transverse lug on said first scar, said lever having a depending arm projecting rearwardly of said trigger in response to the pivotal movement transmitted thereto by said rst sear, said lever arm being arranged to contact the trigger guard during retraction of said trigger to said second firing position and thereby pivot said lever to hold said rst sear out of engagement with the striker prior to release of said trigger, and a longitudinally reciprocable actuator bar for contacting said transverse lug on said second sear during each cycle of operation to pivot said sear out of cocking engagement with the striker and thereby eiiect automatic lire while said trigger is being held in said second firing position.

References Cited in the le of this patent UNITED STATES PATENTS 

